Pre-up, post-up, pre-down, and post-down hooks

These are programs that, if they exist, will run before or after the
syncronization/removal is run. Three use cases caused this:

1. The thoughtbot dotfiles will run a vundle installation set of
commands after intitial synchronization.

2. I changed the location of `.bash_history` to `.bash/history` and
wanted to move `.bash_history` to `.bash/history` after up to preserve
existing history.

3. Moving from an existing old-style custom install script to `rcup`
might require some cleanup; this happened in practice, and required a
simple script.

7 files changed, 63 insertions, 6 deletions

diff --git a/NEWS.md.in b/NEWS.md.in
index 2934419..0e7c8df 100644
--- a/NEWS.md.in
+++ b/NEWS.md.in
@@ -6,6 +6,7 @@ rcm (@PACKAGE_VERSION@) unstable; urgency=low
  * Copy instead of symlink with -C.
  * Always copy the files listed in COPY_ALWAYS.
  * Show whether the file is a copy or symlink using lsrc -F.
+ * Add hooks for pre-up, post-up, pre-down, and post-down.
 
  -- Mike Burns <mburns@thoughtbot.com>  Mon, 05 Aug 2013 16:43:33 +0200
 
diff --git a/bin/lsrc b/bin/lsrc
index f7f4826..1ea2e2c 100755
--- a/bin/lsrc
+++ b/bin/lsrc
@@ -140,7 +140,7 @@ is_metafile() {
   host_portion=`echo $1 | sed -e 's/host-.*/host-/'`
   tag_portion=`echo $1 | sed -e 's/tag-.*/tag-/'`
 
-  [ x$host_portion = 'xhost-' -o x$tag_portion = 'xtag-' ]
+  [ x$host_portion = 'xhost-' -o x$tag_portion = 'xtag-' -o "x$1" = "xhooks" ]
 }
 
 dotfiles_dir_excludes() {
diff --git a/bin/rcdn b/bin/rcdn
index d809796..cae9dc8 100755
--- a/bin/rcdn
+++ b/bin/rcdn
@@ -70,6 +70,9 @@ if [ -e $HOME/.rcrc ]; then
 fi
 
 handle_command_line $*
+: ${DOTFILES_DIRS:=$DOTFILES_DIRS $DEFAULT_DOTFILES_DIR}
+
+run_hooks pre down
 
 for dest_and_src in `lsrc $LS_ARGS`; do
   saved_ifs=$IFS
@@ -81,3 +84,5 @@ for dest_and_src in `lsrc $LS_ARGS`; do
 
   remove_link $dest $dest $sigil
 done
+
+run_hooks post down
diff --git a/bin/rcup b/bin/rcup
index 5f51192..5a42a81 100755
--- a/bin/rcup
+++ b/bin/rcup
@@ -119,13 +119,13 @@ handle_command_line() {
   handle_common_flags rcup $version $verbosity
 
   tags=${arg_tags:-$TAGS}
-  dotfiles_dirs=${dotfiles_dirs:-$DOTFILES_DIRS}
+  DOTFILES_DIRS=${dotfiles_dirs:-$DOTFILES_DIRS}
   files=$@
 
   for tag in $tags; do
     LS_ARGS="$LS_ARGS -t $tag"
   done
-  for dotfiles_dir in $dotfiles_dirs; do
+  for dotfiles_dir in $DOTFILES_DIRS; do
     LS_ARGS="$LS_ARGS -d $dotfiles_dir"
   done
   for exclude in $excludes; do
@@ -146,6 +146,9 @@ if [ -e $HOME/.rcrc ]; then
 fi
 
 handle_command_line $*
+: ${DOTFILES_DIRS:=$DOTFILES_DIRS $DEFAULT_DOTFILES_DIR}
+
+run_hooks pre up
 
 for dest_and_src in `lsrc $LS_ARGS`; do
   saved_ifs=$IFS
@@ -162,3 +165,5 @@ for dest_and_src in `lsrc $LS_ARGS`; do
 
   handle_file $src $dest $sigil
 done
+
+run_hooks post up
diff --git a/man/rcdn.1 b/man/rcdn.1
index 6c641c9..24ca1a2 100644
--- a/man/rcdn.1
+++ b/man/rcdn.1
@@ -30,6 +30,17 @@ is, that directory is removed. If a rc file is not a symlink but is
 listed in
 .Va COPY_ALWAYS
 the file is removed.
+.Pp
+The
+.Nm
+program will run hooks before and after removing files, if these hooks
+exist. Hooks are executable programs inside the dotfiles directory, with
+the following names:
+.Pa hooks/pre-down and
+.Pa hooks/post-down .
+These hooks are run each time
+.Nm
+is run and therefore must be idempotent.
 .
 .Bl -tag
 .It Fl d Ar DIR
diff --git a/man/rcup.1 b/man/rcup.1
index 99fa364..4140205 100644
--- a/man/rcup.1
+++ b/man/rcup.1
@@ -84,7 +84,8 @@ option in
 .Xr rcrc 5
 can be used to list files that must only be copied.
 .Pp
-Two meta files are supported: host-specific files and tagged files.
+Three meta files are supported: host-specific files, tagged files,
+hooks.
 .Pp
 Host-specific files go in a directory named for the host, prefixed with
 .Pa host- .
@@ -93,8 +94,7 @@ For example,
 contains files specific to the computer with hostname
 .Pa scarlett
 , and these files will only be installed on the computer with hostname
-.Pa scarlett
-\&.
+.Pa scarlett .
 .Pp
 Tagged files go in a directory named for the tag, prefixed with
 .Li tag- .
@@ -103,18 +103,33 @@ Therefore, files under
 are only installed when installing using the
 .Li git
 tag.
+.Pp
+Hooks go in a directory named
+.Pa hooks .
+Two hooks are supported by
+.Nm rcup :
+pre-up and post-up . These go in files with predictable filenames:
+.Pa .dotfiles/hooks/pre-up and
+.Pa .dotfiles/hooks/post-up .
+These files must be executable. They are run every time
+.Nm
+is run, and therefore must be idempotent.
 .Sh ALGORITHM
 It is instructive to understand the process
 .Nm rcup
 uses when synchronizing your rc files:
 .Bl -enum
 .It
+The pre-up hook is run.
+.
+.It
 All non-host, non-tag files without a dot prefix are symlinked to the
 dotted filename in your home directory. So,
 .Pa .dotfiles/tigrc
 is
 symlinked to
 .Pa ~/.tigrc .
+.
 .It
 All non-host, non-tag directories have their structure copied to your
 home directory, then a non-dotted symlink is created within.  So for
@@ -125,12 +140,14 @@ causes the
 directory to be created, then
 .Pa haskell.vim
 is symlinked within.
+.
 .It
 Steps (1) and (2) are applied to host-specific files. These are files
 under a directory named
 .Sm off
 .Pa host- Va $HOSTNAME .
 .Sm on
+.
 .It
 Steps (1) and (2) are applied to tag-specific files. These are files
 under directories named
@@ -142,6 +159,9 @@ where
 is the name of each specified tag in turn, taken from the command line
 or from
 .Xr rcrc 5 .
+.
+.It
+The post-up hook is run.
 .El
 .
 .Sh FILES
diff --git a/share/rcm.sh.in b/share/rcm.sh.in
index ea35e47..36b6762 100644
--- a/share/rcm.sh.in
+++ b/share/rcm.sh.in
@@ -99,3 +99,18 @@ handle_metadata_flags() {
   $DEBUG "TAGS: $TAGS"
   $DEBUG "DOTFILES_DIRS: $DOTFILES_DIRS"
 }
+
+run_hooks() {
+  $DEBUG "run_hooks $1 $2"
+  $DEBUG "  with DOTFILES_DIRS: $DOTFILES_DIRS"
+  local when=$1
+  local direction=$2
+
+  for dotfiles_dir in $DOTFILES_DIRS; do
+    $DEBUG "hook: $dotfiles_dir/hooks/$when-$direction"
+    if [ -x "$dotfiles_dir/hooks/$when-$direction" ]; then
+      $VERBOSE "running $when-$direction hooks for $dotfiles_dir"
+      $dotfiles_dir/hooks/$when-$direction
+    fi
+  done
+}